Using a Not Equals Conditions when defining Charge Account derivation rules

Summary

How do I set a Not Equals condition when defining Charge Account derivation rules

Content

There was a recent query about how to define a condition of 'Not Equals' when defining Transaction Account Builder rules to derive a charge account. In this use case, the customer had a requirement to specifically use 'Not Equals'. Two tips here:

a) The customers cannot use Equals or Not Equals condition types. They ought to use Matches

b) The expression to use for 'Not Equals' is '?!'

I thought as a tip this might come in handy when defining rules with complexity.